Hydrogen Bond Dynamics of Cellulose through Inelastic Neutron Scattering Spectroscopy
authors Araujo, C; Freire, CSR; Nolasco, MM; Ribeiro-Claro, PJA; Rudic, S; Silvestre, AJD; Vaz, PD
nationality International
journal BIOMACROMOLECULES
keywords DENSITY-FUNCTIONAL THEORY; FT-RAMAN-SPECTROSCOPY; SYNCHROTRON X-RAY; INFRARED-SPECTROSCOPY; I-BETA; VIBRATIONAL-SPECTRA; NATIVE CELLULOSE; TERAHERTZ SPECTROSCOPY; AMORPHOUS CELLULOSE; FIBER DIFFRACTION
abstract This work explores the dynamics of hydrogen bond networks in cellulose through inelastic neutron scattering (INS) and periodic CASTEP calculations. Estimated spectra were based on the crystal structure of cellulose I alpha and I beta and replicate the INS spectrum of cellulose samples with remarkable similarity, allowing a reliable assignment of INS bands to vibrational modes of cellulose. Comparison of cellulose samples from varied sources, from bacterial to kraft pulp, allows the identification of characteristic INS bands, arising from C2-OH torsional motions, which easily identify which allomorph-I alpha or I beta-is prevalent. A high crystallinity index is revealed by the presence of well-defined INS bands associated with highly cooperative CH bending modes along the chain. Hydrating kraft cellulose samples clearly affects those INS bands related with the hydroxymethyl group, identified as the preferred binding site for water molecules. At high humidity content level, a significant proportion of the water molecules is aggregated in clusters within the amorphous cellulose domains. The formation of ice microcrystals leads to a partial disruption of the hydrogen-bond network, as can be concluded from the observed red-shift of the torsional OH vibrational modes. The full assignment and interpretation of cellulose's INS spectra herein provided is a sound basis for future use of INS spectroscopy in the characterization of functionalized cellulose fibers and composite materials.
publisher AMER CHEMICAL SOC
issn 1525-7797
year published 2018
volume 19
issue 4
beginning page 1305
ending page 1313
digital object identifier (doi) 10.1021/acs.biomac.8b00110
web of science category Biochemistry & Molecular Biology; Chemistry, Organic; Polymer Science
subject category Biochemistry & Molecular Biology; Chemistry; Polymer Science
unique article identifier WOS:000429886500021

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